Doley Amolina, Mahto Vikas, Rajak Vinay Kumar, Kiran Raj, Upadhyay Rajeev
Department of Petroleum Engineering, IIT (ISM) Dhanbad, Dhanbad, Jharkhand 826004, India.
ACS Omega. 2024 May 1;9(19):21365-21377. doi: 10.1021/acsomega.4c01632. eCollection 2024 May 14.
Hydrated shale formations often lead to severe drilling problems and may lead to wellbore instability. These instabilities can result in issues such as bit balling, borehole collapse, formation damage, stuck pipe, and low drilling rates. Keeping these fundamental issues with drilling in shale formation in mind, this study is aimed at designing a water-based drilling fluid system for effective shale inhibition, ensuring enhanced wellbore stability and drilling efficiency. The designed mud system comprises a typical base fluid along with newly synthesized chitosan derivative chitosan--(2-hydroxyl)-propyl trimethylammonium chloride (HACC) as an additive. This additive was found to be soluble in water and conducive for shale inhibition. The derived product was characterized by field emission scanning electron microscopy, thermogravimetric analysis, and Fourier-transform infrared spectroscopy (FTIR). Various drilling fluid tests, including filtration and rheological experiments, were conducted to evaluate its proficiency as a drilling mud additive. The results showed improvement in rheological and filtration properties after hot rolling at 100 °C in comparison to a conventional shale inhibitor, polyethylenimine. As we increase the concentration of synthesized chitosan derivative from 0.3 to 1.5 w/v%, the filtration loss is reduced from 40% to 65% as compared to the base fluids. Shale recovery tests were also conducted using shale samples from an Indian field to assess its viability for field application. The addition of 0.3 to 1.5 w/v% chitosan derivative resulted in high shale recovery above 88% to 96% at 100 °C compared to polyethylenimine, which showed a change in recovery from 62% to 73%. HACC intercalates into clay platelets, reducing the interlayer spacing between particles and preventing clay from hydrating and swelling. This mechanism of inhibition is evaluated by X-ray diffraction, FTIR, and zeta potential analysis. This bolsters the hypothesis of using the synthesized chitosan derivative as a shale inhibitor.
水合页岩地层常常导致严重的钻井问题，并可能致使井眼不稳定。这些不稳定情况会引发诸如钻头泥包、井壁坍塌、地层损害、卡钻以及低钻速等问题。鉴于页岩地层钻井存在的这些基本问题，本研究旨在设计一种水基钻井液体系，以实现有效的页岩抑制，确保提高井眼稳定性和钻井效率。所设计的泥浆体系包含一种典型的基液以及新合成的壳聚糖衍生物壳聚糖 -（2 - 羟基）- 丙基三甲基氯化铵（HACC）作为添加剂。发现该添加剂可溶于水且有利于页岩抑制。通过场发射扫描电子显微镜、热重分析和傅里叶变换红外光谱（FTIR）对所得产物进行了表征。进行了包括过滤和流变实验在内的各种钻井液测试，以评估其作为钻井泥浆添加剂的性能。结果表明，与传统页岩抑制剂聚乙烯亚胺相比，在100℃热滚后其流变和过滤性能有所改善。当我们将合成壳聚糖衍生物的浓度从0.3增加到1.5 w/v%时，与基液相比，滤失量从40%降低到65%。还使用来自印度某油田的页岩样品进行了页岩回收率测试，以评估其在现场应用的可行性。与聚乙烯亚胺相比，添加0.3至1.5 w/v%的壳聚糖衍生物在100℃时导致页岩回收率高达88%至96%，而聚乙烯亚胺的回收率从62%变为73%。HACC插入粘土片层之间，减小颗粒间的层间距，防止粘土水化和膨胀。通过X射线衍射、FTIR和zeta电位分析对这种抑制机制进行了评估。这支持了使用合成壳聚糖衍生物作为页岩抑制剂的假设。
